A 3D sliding bearing finite element based on the Bouc-Wen model : Implementation in Abaqus

University essay from KTH/Bro- och stålbyggnad

Abstract: As rail transportation is significantly more virtuous than airplanes or cars in terms of greenhousegases emissions, its development is being encouraged in several European countries, includingSweden. In addition, the development of railway lines on which trains can travel at higher speeds ismade in Sweden with the integration of existing infrastructure. On railway bridges, an increased trainspeed potentially leads to an increase in vibrations during passage, for which the structure may not bedesigned. It is therefore essential to know the dynamic properties of the structures used.Several studies highlight the influence of friction phenomena in sliding bearings on the dynamicproperties of bridges equipped with them. This Master Thesis is based on previous works that led tothe development of a finite element modelling the friction mechanisms that occur in these bearings.The friction occurring between a PTFE sliding plate and a steel surface is thus modelled using the Bouc-Wen model, a model for hysteresis phenomena. The finite element was developed as a Fortransubroutine, which can be integrated into the finite element calculation software Abaqus as a "userdefinedelement". It allows friction to be modelled along the longitudinal direction of the bridge onlyand can therefore only be used in two-dimensional models. The user-defined element is also based ona model that takes into account the influence of contact pressure and sliding velocity on the steel-PTFEcoefficient of friction. As several studies indicate, contact temperature can also have a significantinfluence on the value of the coefficient of friction but is not taken into account in the current model.In this project, the previously developed finite element was therefore generalized to account forfriction in both directions of the sliding plate by the means of a two-dimensional generalization of theBouc-Wen model. Based on experimental data available in scientific literature, the model forcalculating the coefficient of friction was also extended to take into account the influence of thecontact temperature. In addition, a model to update the contact temperature based on the theory ofsurface heating of semi-infinite bodies has been incorporated. Finally, this thesis presents theintegration of this updated finite element on three-dimensional models of the Banafjäl Bridge, locatedin northern Sweden. Simulations to estimate the fundamental frequencies and resonance modes ofthe structure as well as the temperature increase that can occur in a bearing during the passage of atrain were carried out on this model.

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